The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingCommunication malfunction no. 1
Description
This dtc is output when a communication error occurs between the transponder
key amplifier and
transponder key ecu. Some possible reasons for the communication error are: 1) 2
or more ignition keys
are positioned too close together, or 2) noise is occurring in the communicatio ...
Ig2 relay
On-vehicle inspection
Disconnect cable from negative battery
terminal
Caution:
Wait at least 90 seconds after disconnecting the
cable from the negative (-) battery terminal to
prevent airbag and seat belt pretensioner activation.
Remove ig2 relay
Remove the no. 1 Engine room re ...
Dtc check / clear
Check dtc
Hint:
When dtc b1650/23 is detected as a result of
troubleshooting for the airbag system, troubleshoot
the occupant classification system.
Use the intelligent tester (with can vim) to read and
clear dtcs, otherwise the dtcs cannot be read and
cleared.
Connect ...